Laminar fluid flow process



y 1962 D. OBRIEN ROSELLE 3,034,526-

LAMINAR FLUID FLOW PROCESS Filed Nov. 13, 1959 3 Sheets-Sheet 1 N. m a

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IO (0 5 X 7 INVENTOR DONALD O'BRIEN ROSELLE y 1962 D. OBRIEN ROSELLE 3,034,526

LAMINAR FLUID FLOW PROCESS Filed Nov. 15, 1959 3 Sheets-Sheet 2 INVENTOR DONALD O'BRIEN ROSELLE ATTORNEY y 15, 1952 D'. OBRIEN ROSELLE 3,034,526

LAMINAR FLUID FLOW PROCESS 3 Sheets-Sheet 3 Filed Nov. 13

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INVENTOR DONALD O'BRIEN ROSELLE ATTORNEY United States Patent 3,034,526 LAMINAR FLUID FLOW PROCESS Donald OBrien Roselle, Springfield, Pa., assignor to E. I. y

This invention relates to the distribution of a viscous fluid under laminar flow conditions from a single source to a plurality of delivery ports. More particularly, it concerns flow systems for slow moving viscous fluids of the type which are subject to time and temperature dependent property variations. The viscous fluids under consideration have 21 Reynolds number of less than one.

Systems for distributing fluid from a single source to a plurality of discharge ports are common and the design techniques for providing even distribution are Well known. A tree-like cascade manifold is one convenient way of dividing a main stream of a fluid into several streams. The distribution can readily be carried out whether the fluid is relatively viscous as oil or relatively non-viscous as water. Similar tree-like cascade manifolds were adapted in many spinning systems for the distribution of molten synthetic polymer from a single source to a plurality of spinning heads.

In the type of spinning system referred to above, a multiplicity of spinning heads spaced some distance apart are supplied from a common inlet which is connected to a long supply line from the source of fiber-forming material. The inlet and the spinning heads are joined through a tree-like cascade of piping branching out from the inlet in increasing pairs of branch channels leading to the spinning heads. The whole system is designed so that the flow times from the inlet to each and every spinning head are substantially equal. Similarly, the flow times from any branching point to the associated spinning heads are substantially equal. The spinning heads are ordinarily linearly aligned because of the distribution of aisles in the usual floor plan. Accordingly, cascades of the type mentioned above are laid out in the plane of the line of spinning heads, thus providing the simplest piping arrangement.

The linear polymeric materials such as nylon, polyethylene terephthalate and the like, which are exemplary of the viscous materials in the synthetic yarn spinning art, will vary in physical properties depending on polymer temperature and residence time. However, despite the attention paid to providing even flow times in the planar cascade system described above, the results achieved in the distribution of the molten, highly viscous, synthetic polymer fluids, have been less than satisfactory. It has been observed that properties of the fluid as discharged from outlets supplied from the same source differ considerably. Not only have these difierences been found at points widely separated in a large cascade, but they have been observed in adjacent positions in a four-outlet cascade. The products issuing from the various outlets differed in viscosity and/or the degree of degradation.

An object of this invention is to distribute time and temperature sensitive fluids in a flow system having a single inlet and a plurality of outlets in a manner substantially eliminating outlet-to-outlet non-uniformities. Another object of this invention is to provide a flow system for accomplishing this.

To attain these objectives, the present invention contemplates the supply of a fluid subject to time and temperature dependent property variations, to a pipeline system comprising an entrance conduit, a T-shaped fluid pipe connector consisting of a section of pipe intersected by a second section of pipe, both said pipe sections lying in a single plane, said entrance conduit operatively connected to said T-shaped fluid connector at the open end of said second pipe section, the two remaining open ends of said T-shaped fluid connector each being operatively connected to an additional similar T-shaped fluid connector at the open end of the pipe section comparable to the second pipe section of said first T-shaped fluid connector, said additional T-shaped fluid connectors lying in planes oriented in space at substantially a angle, with respect to the plane of said first T-shaped fluid connector, the remaining open ends of said additional T-shaped fluid connectors communicating with means for conducting the fluid to separate outlets.

As pointed out above, the appartaus is particularly suitable in flow system for molten polymer.

In the ordinary case of laminar polymer flow through pipe from the source to the spinning heads Where time and temperature conditions are significant, the wall contacting and adjacent portions of the fluid stream, referred to herein as wall material, will differ both physically and chemically from the center and adjacent portions of said fluid stream, referred to as core material, the difference being proportional to the velocity distribution along a cross-section of the fluid stream perpendicular to the direction of flow. The core portion at the center of the initial feed stream and the wall portion at the circumference of the stream will differ materially from each other. At intermediate points, material intermediate in character to both the core and wall portions will be present, its exact nature being dependent on its distance from the center along a radius from the center of the stream to a point on the circumference. For example, at a point on the radius closer to the center of the stream than to the wall, the material will be more like that at the center than the material at a point closer to the wall.

At some point along the radius, the material will have the characteristics of both wall and core center material to the same degree. In the accompanying drawings showing a cross-section of the polymer stream, the boundaries of the dotted areas with the clear areas, schematically represent such material. The dotted areas schematically represent core material and the clear areas, wall material.

Examination reveals that the core portion is moving faster, and because it is exposed to high temperatures for a shorter time, it is less thermally degraded than the Wall material. The process of the invention mitigates the eflect of this distribution by assuring that the fluid issuing from each outlet contains substantially similar proportions of core and wall material of the original polymer feed stream. This is accomplished by dividing the first polymer supply stream along its ads of symmetry with respect to core and wall portions into two substantially equal streams, each having substantially similar proportions of core and Wall materials of said first polymer supply stream. A T-shaped or Y-shaped branching device may accomplish the division. Each of these two streams is again divided at a branching point along its axis of symmetry into two substantially equal streams, resulting in a total of four streams which have substantially similar proportions of core and wall material of said first polymer supply stream. Each of the four resulting streams may be divided at subsequent branching points providing in each instance, as above, for the equi-proportional division of core and wall portions of said first polymer supply stream. By axis of symmetry is meant a straight line bisecting the cross-section of the fluid stream so that the polymer compositions on each side of the line are substantially identical in all respects and in particular in their content of core center, wall and intermediate material. In the above described system, the volume and rate of flow from the a original branching point to any of the subsequent outlets must be substantially equal, in order for each spinning head to receive polymer of similar physical properties in the same period of time, from that branching point.

In the figures, FIGURE 1 is a schematic of the threedimensional cascade of the instant invention. FIGURES 2, 3, and 4 are transverse sections taken along the lines XX, YY, and 22 of FIGURE 1, respectively. They show the approximate position of the core and wall material at various points in the flow system. Again it should be noted that the dotted cross-hatched portion is merely a schematic illustration of material which is more nearly like that which is at the center of the initial polymer stream while the clear cross-hatched area represents material which is more nearly like that which is at the circumference of the initial polymer stream. FIGURE 5 is a plan view in cross-section of a preferred embodiment of a three-dimensional cascade according to the invention, enclosed in a unitary heating jacket, and FIGURE 6 is an elevational view in cross-section of the preferred embodiment of FIGURE 5. FIGURE 7 is a schematic of a 3- dimensional cascade in accordance with the present invention containing a plurality of elbows and T-shaped branching points. FIGURE 8 shows transverse sections taken along the lines A-A, BB, CC, and D-D of FIG- URE 7 respectively.

FIGURE 1 is the three-dimensional cascade of the instant invention. Polymer 10 composed of core material 8 and wall material 9 flowing in the direction of the arrow through supply line 11 enters T 12 and divides against the far wall into branches 13 and 14. At Ts 15 and 16, which are in planes at 90 to the plane of T 12, the polymer is delivered along the walls of branches 13 and 14 in a manner locating it centrally between branches 17 and 18 and 19 and 20, respectively. Outlets 21, 22, 23, and 24 are seen to obtain equal portions of the original core mate- 'rial 8, as well as equal portions of'the original wall material 9. When considering the flow patterns of FIGURE 1, it should be remembered that the material from wall to wall is continuously in motion and that the velocity distribution varies from wall to center and then back to wall again in a parabolic velocity gradient across the supply line with the flow down the core of the pipe significantly faster than the flow near the wall of the pipe.

It has been found that flow through pipe elbows does not disturb this yelocity distribution to any significant degree. The hold-up time distribution approaches ideal uniformity in the three-dimensional cascade of FIGURE 1 resultant from the redistributing eflect obtained at the subsequent T connections. The Ts or T-shaped fluid connectors which are referred to herein are bull Ts in contrast with the normal T. A bull T is one in which the inlet comes in the single line perpendicular to the T with the outlets going out the cross of the T. That is, the two outlet pipes are on the same axis. This is in contrast to normal procedure, where the inlet comes in on the same axis as one of the outlets and the second outlet branches ofl at 90 to the inlet and the other outlet. At a bull T the core material flows to the farthest Wall of the T and then divides along that wall. A cascade such as that of FIGURE 1' may be extended as required to obtain the desired number of outlets, each successive branchingsystem being located in a plane rotated from the preceding, and where the original core material is substantially equally divided at the subsequent T. Where more than two successive Ts are employed, the approximation to ideal is exemplary of materials falling within this range. Polymer composed of core material 108 and wall material 109 flowing through supply line 111 enters T 112 and divides against the far wall into branches 113 and 114. At T 115 the polymer again divides against the far wall into branches 117 and 118. The polymer in branch 117 turns at elbow 119 and enters T 120 where it again divides against the far wall into branches 121 and 122. The polymer in branch 121 enters T 123 and divides against the far Wall into branches 124 and 125 each of which branches feeds polymer to Ts 126 and 127 respectively. Polymer entering T 126 is divided against the far wall into branches 128 and 129 which may lead to a further branching or to outlet heads. FIGURE 8 is a schematic showing the cross-section of the fluid stream at various points in the system, the shaded areas indicating core material and the cross-hatched areas indicating wall material.

FIGURES 5 and 6 show a practical application of the three-dimensional cascade of FIGURE 1 to a manifold for a linear polymer spinning machine. The cascade is enclosed in a unitary heating jacket 40. Polymer enters flange 41 flowing in the direction of arrow C in supply line 42, passes through reducing elbow 43 to T 44 into main branch lines 45 and 46. Flow through main branch line 45 is through elbow 47 into special T 48, which lies in a plane 90 to the plane of T 44. In special T 48 the flow divides into sub-branches 49 and 59 leading to outlet ports 51 and 52, respectively. Special T 48 is characterized by an extended body so that thermocouples and/ or pressure control instrumentation may be inserted through the unitary heating jacket 40 without destroying its physical integrity. Flow through main branchline 46 is similar, passing through special T 53 there dividing into sub-branch lines 5'4 and 55 supplying outlet ports 56 and 57, respectively.

Unitary heating jacket 40 may be made of welded construction from standard pipe and pipe fittings. In the embodiment shown in FIGURES 5 and 6 it is composed of a main body 58 composed of an appropriate section of heavy-walled pipe capped at one end by cap 59 and at the other by flange cap 60. Heat transfer medium, which may well be a condensing vapor, flows in the direction of arrow A through flanged entry fitting 61 and returns in the direction of arrow B through flanged outlet pipe 62. Sub-branch lines 49, 50, 54 and 55 are led to their respective outlet ports 51, 52, 56, and 57 through subsidiary jackets 63, 64, 65, and 66. The essential feature of this unitary jacket design is that the three-dimensional cascade system of pipes has been collapsed into a compact bundle such that all the pipes are contained in a single vapor heating jacket. This makes the cascade piping as short as possible consistent with the use of a cascade system. It reduces the number of joints on both the main flow side and the vapor side with consequently less opportunity for leaks and limits the external heat radiating area as compared with a more conventional pipe and jacket system, thus less heat needs to be furnished. Furthermore, costs of ventilation and airconditioning are reduced. Other advantages of the unitary jacket surrounding a collapsed cascade are: the system is smaller and simpler resulting in lower insulation cost and in reduced head room; all welds can be made and leak tested in a weld shop, as field welding may beeliminated; and stresses in the pipe due to differential thermal flow is not obtained by a 90 rotation. It is determined tory for viscous fluids in the range of 500 to 2,500 poise viscosity, when Reynolds number is less than 0.1. Nylon expansion are minimized because all of the cascade piping surface is exposed-to the heat transfer medium.

7 Enclosure of a cascade within a unitary jacket may be attained by methods such as providing a longitudinal split in the jacket, providing slip joints in the manifold, and welding the joints after the manifold is placed in the jacket. It is also possible prior'to'connecting the outermost runs of the sub branch lines and prior to attaching the subsidiary'jackets to slide the collapsed pipe bundle of'the cascade into the jacket endwise, eliminating a longitudinal jacket weld. Depending upon the requirementsof the system, pipe hangers may be provided to support the interior lines. Where a heating vapor is used, the entire system may be pitched so that condensate runs under the action of gravity to the heat transfer fluid outlet pipe 62.

The present invention constitutes a significant advance over the planar cascade in which a combination of two or more TS in the same or parallel planes are assembled. Despite the provision of equal center line distance in a planar cascade, it cannot provide equal average residence time because the parabolic velocity distribution in the supply line combines with the separating action of the Ts to deliver unequally aged material to adjacent branch lines.

While the above description referred to Ts or T-shaped piping arrangements as the means for dividing the streams, Y-shaped connections are also suitable.

What is claimed is:

1. In a process for delivering under laminar flow, a time and temperature sensitive viscous polymer from a single inlet to a plurality of outlets in such a manner that the material originally presented to the inlet is delivered to each of the outlets in substantially the same physical and chemical condition, the improvement comprising dividing the original polymer supply stream having core and Wall portions along an axis of symmetry at a branching point into two substantially equal streams, each having substantially similar proportions of core and wall material of said original polymer stream and again dividing a resulting stream along its axis of symmetry at a branching point into two substantially equal streams, each having substantially similar proportions of core and wall material of said original polymer stream.

2. The process of claim 1 wherein resulting streams are divided at subsequent branching points while maintaining the equi-proportional division of core and wall material of said original polymer supply stream.

References Cited in the file of this patent UNITED STATES PATENTS 

